More on Amenas, Algeria from NY Times

Goal was to blow up plant (inflicting major blow on Algerian economy) NOT to take hostages -

...Now it seems clear that the siege was about more than disabling the plant, and that holding hostages for ransom was not part of the plan. Instead, the militants sought to orchestrate a spectacular fireball that could have killed everyone in the vicinity. While that plot could offer more justification for the Algerian government’s take-no-prisoners response, questions remain about whether the standoff could have been ended with fewer lives lost....

Attackers had help from inside -

What appears increasingly certain is that the attackers benefited from inside help. They used a map to guide them around the facility, and at least one of them had once worked at the plant as a driver, officials said. But what the militants lacked was the technical expertise to execute the dramatic ending that some captives say was envisioned.

BUT they had no idea how to actually blow up plant.

[link to nyti.ms]

Two Theories -

(My original theory) 1) Someone inside Algerian gov't was trying to destabilize the current power structure and rented some Jihadists to help - explains why crucial plant was struck at the exact right moment (when foreign VIPs were there) or
(FSB Connection?) 2) Russians did it? Maybe to take out a Nat Gas competitor (and thus strengthen their own exports) or to weaken pro-Western elements in their old friend - Algeria?

Those are just a couple of guesses - whatever happened - it is looking less likely that the Marlboro Man pulled off this major attack on his own, especially given the fact that he was thrown out of AQIM a couple of months ago...